199 research outputs found

### External leg amputation in conformal invariant three-point function

Amputation of external legs is carried out explicitly for the conformal
invariant three-point function involving two spinors and one vector field. Our
results are consistent with the general result that amputing an external leg in
a conformal invariant Green function replaces a field by its conformal partner
in the Green function. A new star-triangle relation, involving two spinors and
one vector field, is derived and used for the calculation.Comment: 16 pages; last paragraph added in Sec. 10, presentation improved, to
appear in Eur. Phys. J.

### Higher spins dynamics in the closed string theory

The general $\sigma$-model-type string action including both massless and
massive higher spins background fields is suggested. Field equations for
background fields are followed from the requirement of quantum Weyl invariance.
It is shown that renormalization of the theory can be produced level by level.
The detailed consideration of background fields structure and corresponding
fields equations is given for the first massive level of the closed bosonic
string.Comment: 11 pages, report TSU/QFTD-36/9

### Generalized Conformal Symmetry in D-Brane Matrix Models

We study in detail the extension of the generalized conformal symmetry
proposed previously for D-particles to the case of supersymmetric Yang-Mills
matrix models of Dp-branes for arbitrary p. It is demonstrated that such a
symmetry indeed exists both in the Yang-Mills theory and in the corresponding
supergravity backgrounds produced by Dp-branes. On the Yang-Mills side, we
derive the field-dependent special conformal transformations for the collective
coordinates of Dp-branes in the one-loop approximation, and show that they
coincide with the transformations on the supergravity side. These
transformations are powerful in restricting the forms of the effective actions
of probe D-branes in the fixed backgrounds of source D-branes. Furthermore, our
formalism enables us to extend the concept of (generalized) conformal symmetry
to arbitrary configurations of D-branes, which can still be used to restrict
the dynamics of D-branes. For such general configurations, however, it cannot
be endowed a simple classical space-time interpretation at least in the static
gauge adopted in the present formulation of D-branes.Comment: 26 pages, no figure

### On "Schwinger Mechanism for Gluon Pair Production in the Presence of Arbitrary Time Dependent Chromo-Electric Field"

Recently the paper "Schwinger Mechanism for Gluon Pair Production in the
Presence of Arbitrary Time Dependent Chromo-Electric Field" by G. C. Nayak was
published [Eur. Phys. J. C 59, 715 (2009); arXiv:0708.2430]. Its aim is to
obtain an exact expression for the probability of non-perturbative gluon pair
production per unit time per unit volume and per unit transverse momentum in an
arbitrary time-dependent chromo-electric background field. We believe that the
obtained expression is open to question. We demonstrate its inconsistency on
some well-known examples. We think that this is a consequence of using the
so-called "shift theorem" [arXiv:hep-th/0609192] in deriving the expression for
the probability. We make some critical comments on the theorem and its
applicability to the problem in question.Comment: 4 page

### Equivalence of partition functions for noncommutative U(1) gauge theory and its dual in phase space

Equivalence of partition functions for U(1) gauge theory and its dual in
appropriate phase spaces is established in terms of constrained hamiltonian
formalism of their parent action. Relations between the electric--magnetic
duality transformation and the (S) duality transformation which inverts the
strong coupling domains to the weak coupling domains of noncommutative U(1)
gauge theory are discussed in terms of the lagrangian and the hamiltonian
densities. The approach presented for the commutative case is utilized to
demonstrate that noncommutative U(1) gauge theory and its dual possess the same
partition function in their phase spaces at the first order in the
noncommutativity parameter \theta .Comment: 15 pages. Version to appear in JHE

### Geometric Second Order Field Equations for General Tensor Gauge Fields

Higher spin tensor gauge fields have natural gauge-invariant field equations
written in terms of generalised curvatures, but these are typically of higher
than second order in derivatives. We construct geometric second order field
equations and actions for general higher spin boson fields, and first order
ones for fermions, which are non-local but which become local on gauge-fixing,
or on introducing auxiliary fields. This generalises the results of Francia and
Sagnotti to all representations of the Lorentz group.Comment: 34 pages, LaTeX. Reference adde

### Volkov-Akulov theory and D-branes

The action of supersymmetric Born-Infeld theory (D-9-brane in a Lorentz
covariant static gauge) has a geometric form of the Volkov-Akulov-type. The
first non-linearly realized supersymmetry can be made manifest, the second
world-volume supersymmetry is not manifest. We also study the analogous 2
supersymmetries of the quadratic action of the covariantly quantized D-0-brane.
We show that the Hamiltonian and the BRST operator are build from these two
supersymmetry generators.Comment: 10 pages, Latex, Contribution to Supersymmetry and Quantum Field
Theory, International Seminar dedicated to the memory of D. V. Volkov
(Kharkov, 1997

### Ramond sector of superconformal algebras via quantum reduction

Quantum hamiltonian reduction of affine superalgebras is studied in the
twisted case. The Ramond sector of "minimal" superconformal W-algebras is
described in detail, the determinant formula is obtained. Extensive list of
examples includes all the simple Lie superalgebras of rank up to 2. The paper
generalizes the results of Kac and Wakimoto (math-ph/0304011) to the twisted
case.Comment: 50 pages, 8 figures; v2: examples added, determinant formula
derivation modified, section order change

### The Topological Unitarity Identities in Chern-Simons Theories

Starting from the generating functional of the theory of relativistic spinors
in 2+1 dimensions interacting through the pure Chern-Simons gauge field, the
S-matrix is constructed and seen to be formally the same as that of spinor
quantum electrodynamics in 2+1 dimensions with Feynman diagrams having external
photon lines excluded, and with the propagator of the topological Chern-Simons
photon substituted for the Maxwell photon propagator. It is shown that the
absence of real topological photons in the complete set of vector states of the
total Hilbert space leads in a given order of perturbation theory to
topological unitarity identities that demand the vanishing of the
gauge-invariant sum of the imaginary parts of Feynman diagrams with a given
number of internal on-shell free topological photon lines. It is also shown,
that these identities can be derived outside the framework of perturbation
theory. The identities are verified explicitly for the scattering of a
fermion-antifermion pair in one-loop order.Comment: 13 pages, LaTex file, one figure (not included

### The geometrical form for the string space-time action

In the present article, we derive the space-time action of the bosonic string
in terms of geometrical quantities. First, we study the space-time geometry
felt by probe bosonic string moving in antisymmetric and dilaton background
fields. We show that the presence of the antisymmetric field leads to the
space-time torsion, and the presence of the dilaton field leads to the
space-time nonmetricity. Using these results we obtain the integration measure
for space-time with stringy nonmetricity, requiring its preservation under
parallel transport. We derive the Lagrangian depending on stringy curvature,
torsion and nonmetricity.Comment: 13 page

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